How to make a array inside array?

PHP Snippet 1:

$data['fileToUpload'] = array_map(
  function($item) {
    return [$item];
  },
  $data['fileToUpload']
);

PHP Snippet 2:

 $myArray = [];
 $myArray['fileToUpload']['name'] = array("file name");
 $myArray['fileToUpload']['type'] = array("file type");
 $myArray['fileToUpload']['tmp_name'] = array("temporary name");
 $myArray['fileToUpload']['error'] = array("error");
 $myArray['fileToUpload']['size'] = array("file size");

 echo "<pre>";
 print_r($myArray);